Sea buckthorn polysaccharides are bioactive components extracted from sea buckthorn. Sea buckthorn polysaccharides have various biological activities such as antioxidant, hypoglycemic, immune regulation, antiviral, antitumor properties. They are beneficial to human health. In the past few decades, the extraction, structural characteristics, and biological activities of sea buckthorn polysaccharides have been extensively studied. This chapter reviews the extraction methods of sea buckthorn polysaccharide, including hot water extraction, chemical extraction, ultrasonic-assisted extraction, microwave-assisted extraction, and supercritical fluid extraction, followed by studies of purification and structural characteristics. Extraction methods can affect the structural characteristics of polysaccharides, further altering their physicochemical properties and biological activity. The biological activities of sea buckthorn polysaccharides, such as anti-inflammatory properties, were also described. This chapter explores the development and application of sea buckthorn polysaccharides in the fields of functional food or medicine.